Please see the link below for more information on the HPC Total Count Samper and other product options. Each sampler is constructed to combine both an intimate contact of a 0.45 µm membrane filter to a nutrient pad, and the incorporation of an air vent on the upper back portion of the paddle. This configuration allows for the draw-through of 1 mL of sample to affix microorganisms to the filter surface for subsequent culturing within its transparent plastic case.
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/418/162/p15325-ms.pdf
For further questions or concerns, please navigate to the link https://www.sigmaaldrich.com/techservice, and click on "Product Technical Inquiries" under the Products Section with all the required information so that a member of the Technical Service team can reach out to assist further. Thank you.